Benzoic acid ba oh 2. Benzoic acid - abstract

Plan

Introduction

Physical properties and occurrence in nature

Chemical properties

Methods for producing monobasic aromatic carboxylic acids

Nitrobenzoic acids

Application

Conclusion

Bibliography

Introduction

Systematic name benzoic acid

Traditional names benzoic acid

Chemical formula C6H5COOH

Molar mass 122.12 g/mol

Physical properties

Condition (standard condition) solid

Thermal properties

Melting point 122.4 °C

Boiling point 249.2 °C

Decomposition temperature 370 °C

Specific heat of vaporization 527 J/kg

Specific heat of fusion 18 J/kg

Chemical properties

Solubility in water 0.001 g/100 ml

Aromatic carboxylic acids are benzene derivatives containing carboxyl groups directly bonded to the carbon atoms of the benzene ring. Acids containing carboxyl groups in the side chain are considered aromatic fatty acids.

Aromatic acids can be divided according to the number of carboxyl groups into one-, two-, or more basic ones. The names of acids in which the carboxyl group is directly bonded to the nucleus are derived from aromatic hydrocarbons. The names of acids with a carboxyl in the side chain are usually derived from the names of the corresponding fatty acids. The acids of the first type are of greatest importance: for example, benzoic (benzenecarbonic) C 6 H 5 -COOH, P- toluyl ( P-toluenecarbonate), phthalic (1,2-benzenedicarboxylic), isophthalic (1,3-benzenedicarboxylic), terephthalic (1,4-benzenedicarboxylic):

Story

It was first isolated by sublimation in the 16th century from benzoin resin (dewy incense), hence its name. This process was described by Nostradamus (1556), and then by Girolamo Ruschelli (1560, under the pseudonym Alexius Pedemontanus) and Blaise de Vigenère (1596).

In 1832, the German chemist Justus von Liebig determined the structure of benzoic acid. He also investigated how it relates to hippuric acid.

In 1875, German physiologist Ernst Leopold Zalkowski investigated the antifungal properties of benzoic acid, which had long been used in fruit canning.

Sulfosalicylic acid

2-Hydroxy-5-sulfobenzoic acid

HO3S(HO)C6H3COOH 2H3O M 254.22

Description

Sulfosalicylic acid is colorless, translucent, needle-shaped crystals or white crystalline powder.

Sulfosalicylic acid is easily soluble in water, alcohol and ether, insoluble in benzene and chloroform, and photosensitive. Aqueous solutions are acidic.

Application

Sulfosalicylic acid is used in medicine for the qualitative determination of protein in urine, and during analytical work to determine the content of nitrates in water.

In industry, sulfosalicylic acid is used as an additive to basic raw materials in the synthesis of substances.

Physical properties and occurrence in nature

Monocarboxylic acids of the benzene series are colorless crystalline substances with a melting point above 100 °C. Acids with pair- the position of the substituents melt at significantly higher temperatures than their isomers. Aromatic acids boil at slightly higher temperatures and melt at significantly higher temperatures than fatty acids with the same number of carbon atoms. Monocarboxylic acids dissolve rather poorly in cold water and much better in hot water. Lower acids are volatile with water vapor. In aqueous solutions, monocarboxylic acids exhibit a greater degree of dissociation than fatty acids: the dissociation constant of benzoic acid is 6.6·10 -5, acetic acid is 1.8·10 -5. At 370C it decomposes to benzene and CO2 (phenol and CO are formed in small quantities). When reacting with benzoyl chloride at elevated temperatures, benzoic acid is converted to benzoic anhydride. Benzoic acid and its esters are found in essential oils (for example, clove, tolu and Peruvian balsam, benzoin). A derivative of benzoic acid and glycine, hippuric acid, is a waste product of animals. It crystallizes in the form of colorless plates or needles, melting at 121 oC, easily soluble in alcohol and ether, but sparingly soluble in water. Currently, benzoic acid is widely used in the dye industry. Benzoic acid has antisentic properties and is therefore used for food preservation. Various benzoic acid derivatives are also widely used.

Chemical properties

Benzene was discovered by Faraday in 1825 and its gross formula was established as C 6 H 6. In 1865, Kekule proposed its structural formula as cyclohexatriene-1,3,5. This formula is still used today, although it, as will be shown later, is imperfect - it does not fully correspond to the properties of benzene.

The most characteristic feature of chemical behavior benzene is the amazing inertness of the carbon-carbon double bonds in its molecule: in contrast to those considered; previously unsaturated compounds, it is resistant to the action of oxidizing agents (for example, potassium permanganate in acidic and alkaline environments, chromic anhydride in acetic acid) and does not enter into the usual electrophilic addition reactions characteristic of alkenes, alkadienes and alkynes.

Trying to explain the properties of benzene by structural features, many scientists, following Kekule, put forward their own hypotheses on this matter. Since the unsaturation of benzene did not clearly manifest itself, it was believed that there were no double bonds in the benzene molecule. Thus, Armstrong and Bayer, as well as Klaus, suggested that in the benzene molecule the fourth valences of all six carbon atoms are directed towards the center and saturate each other, Ladenburg - that the carbon skeleton of benzene is a prism, Chichibabin - that in benzene the carbon is trivalent.

Thiele, improving Kekule's formula, argued that the double bonds in the latter are not fixed, but constantly move - “oscillate”, and Dewar and Hückel proposed structural formulas of benzene with double bonds and small rings.

Currently, based on numerous studies, it can be considered firmly established that the six carbon and six hydrogen atoms in the benzene molecule are in the same plane and that the clouds of π-electrons of the carbon atoms are perpendicular to the plane of the molecule and, therefore, parallel to each other and interact with each other. The cloud of each π-electron is overlapped by the clouds of π-electrons of neighboring carbon atoms. A real benzene molecule with a uniform distribution of π-electron density throughout the ring can be represented as a flat hexagon lying between two tori.

It follows that it is logical to depict the formula of benzene in the form of a regular hexagon with a ring inside, thereby emphasizing the complete delocalization of π-electrons in the benzene ring and the equivalence of all carbon-carbon bonds in it. The validity of the latter conclusion is confirmed, in particular, by the results of measuring the lengths of C-C bonds in the benzene molecule; they are identical and equal to 0.139 nm (C-C bonds in the benzene ring are shorter than single ones (3.154 nm), but longer than double ones (0.132 nm)). Electron density distribution in a benzene molecule; bond lengths, bond angles

A very important derivative of benzoic acid is its acid chloride - benzoyl chloride. It is a liquid with a characteristic odor and a strong lachrymatory effect. Used as a benzoylating agent.

Benzoyl peroxide used as an initiator for polymerization reactions, and also as a bleaching agent for edible oils, fats, and flour.

Toluic acids. Methylbenzoic acids are called toluic acids. They are formed during the partial oxidation of o-, m- And P-xylenes. NN -Diethyl- m-toluilmide is effective repellent- insect repellent:

n-tert-Butylbenzoic acid is produced on an industrial scale by liquid-phase oxidation rubs-butyltoluene in the presence of a soluble cobalt salt as a catalyst. Used in the production of polyester resins.

Phenylacetic acid obtained from benzyl chloride through nitrile or through organomagnesium compounds. This is a crystalline substance with m.p. 76 °C. Due to the mobility of similar atoms of the methyl group, it easily enters into condensation reactions. This acid and its esters are used in perfumery.

Aromatic acids undergo all the reactions that are characteristic of fatty acids. Reactions involving the carboxyl group produce various acid derivatives. Salts are obtained by the action of acids on carbonates or alkalis. Esters - by heating a mixture of acid and alcohol in the presence of mineral (usually sulfuric) acid:

If the substituents in ortho- If this is not the case, then esterification of the carboxyl group occurs as easily as in the case of aliphatic acids. If one of ortho-positions are substituted, the rate of esterification is greatly reduced, and if both ortho- the positions are occupied, esterification usually does not occur (spatial difficulties).

Ethers ortho-substituted benzoic acids can be obtained by the reaction of silver salts with haloalkyl (esters of sterically hindered aromatic acids are easily and quantitatively saponified in the presence of crown ethers). Due to spatial constraints, they are difficult to hydrolyze. Groups larger than hydrogen fill the space around the carbon atom of the carboxyl group to such an extent that they make the formation and saponification of the ester difficult.

Preparation of C6H5COOH:

Main methods:

1. By oxidation of a wide variety of benzene derivatives having one side chain, for example, toluene, ethylbenzene, benzyl alcohol, etc.: C6H5CH3 ® C6H5COOH

2. From benzonitrile, which is hydrolyzed with an acid or alkali for this purpose: 2H2 O C6H5CN ¾¾® C6H5COOH + NH3

Benzoic acid (or rosemary), Acidum benzoicum sublimatum, Flores Benzoës - a very common substance in nature with the composition C7H6O2, or C6H5-COOH; found in some resins, balms, in herbaceous parts and in the roots of many plants (according to previous, still untested observations), as well as in the flowers of Unona odoratissima (in the essence of Alan-Gilan, or ylang-ylang), in beaver stream, but mainly in benzoin resin, or dew incense, hence its name. There are indications about the products of dry distillation of this resin in works dating back to the 16th century; Blaise de Vigenère, in his treatise (1608) "Traité du feu et du sel", was the first to mention a crystalline substance of benzoin gum, which was subsequently examined more closely and received the name Flores benzoës. Its composition was finally established by Liebig in 1832, and Kolbe proposed to consider it as phenylcarboxylic acid. B. acid can be obtained synthetically from benzene and is formed in many reactions occurring with aromatic bodies. For pharmaceutical needs, they use exclusively acid obtained by sublimation of benzoin resin. It is best to take Siamese dew incense for this purpose, since it does not contain cinnamic acid, or Calcutta, which is cheaper and also contains a lot of B. acid. The crushed resin is slightly heated in a sand bath in iron pots, during which the mass first melts and then releases heavy acid vapors, which settle on the cold parts of the device in the form of crystals. To collect the substance, the pot is covered with a paper cone or a lid with a wide tube through which the vapors are discharged into a wooden box covered with paper. At the end of the operation (and strong heating should be avoided if possible), the acid remains in the receiver or on the paper cone in the form of snow-white crystals or flakes. The preparation obtained in this way has a distinct smell of vanilla, which depends on the content of a small amount of essential oil in the resin. Better yields can be achieved by infusing finely ground resin with milk of lime or soda for a long time. The mixture is then heated until the resin melts, and the substance is separated from the resulting benzoic acid salt with hydrochloric acid. The acid obtained in this way has a weaker odor than that obtained by sublimation. For technical purposes, hippuric acid (see this next) contained in the urine of herbivores is taken as a starting material. The urine is quickly evaporated to ⅓ of the original volume, filtered and treated with excess hydrochloric acid, and hippuric acid is released in crystalline form. After 24 hours, the crystals are separated from the mother liquor and purified by repeated crystallization until the persistent smell of urine has almost completely disappeared. Purified hippuric acid is boiled with hydrochloric acid, which splits into B. acid and glycol:

HOOC-CH3 + H3O = HOOC-CH3(NH3) + C6H5-COOH.

In large quantities, B. acid can be obtained from toluene C6H5-CH3, oxidizing it with nitric acid; but it is more profitable (as is practiced in factories) to take for this purpose not toluene, but benzenyl chloride C6H5CCl3; this latter is heated with water in hermetically sealed vessels; the acid formed in this way stubbornly retains halogenated products. Further, B. acid is obtained by heating the lime salt of phthalic acid with caustic lime; finally, significant quantities of it remain as a by-product during the fabrication of bitter almond oil due to the oxidation of the latter. The acid obtained in one way or another is purified by recrystallization from hot water; solutions are decolorized by treatment with animal charcoal or heating with weak nitric acid. Kekule obtained benzoic acid synthetically by reacting carbonic acid on bromobenzene in the presence of sodium metal:

C6H5Br + 2Na + CO2 = C6H5CO2Na + NaBr.

Friedel and Crafts prepared it directly from benzene and carbonic acid in the presence of aluminum chloride. Pure B. acid presents as colorless single-clinomer needles or tablets, ud. weight 1.2 (at 21°), not changing in the light, while the one obtained by sublimation from dewy incense turns yellow after some time due to the decomposition of the essential oil contained in it. The substance melts at 121.°4 C., boils at 249°.2 without decomposition and sublimes below the boiling point; has no smell. Its vapors act as an irritant on the mucous membranes of the respiratory organs. With water vapor, the acid flies below 100°, and therefore its aqueous solutions cannot be concentrated by evaporation. 1000 parts of water are dissolved at 0° 1.7 wt. hours, and at 100° 58.75 hours B. acid. It is also highly soluble in alcohol, ether, chloroform, essential and fatty oils. Some impurities, even in very small quantities, change its physical properties so dramatically that at one time the existence of an isomeric B. acid was recognized and called salic acid, but both substances turned out to be completely identical (Beilstein). When vapor is passed through highly heated pumice or, better yet, dry distillation with caustic barite or slaked lime, the acid breaks down into benzene and carbon dioxide. When fused with caustic potash, all three hydroxybenzoic acids are obtained along with other products; oxidizing agents have a rather difficult effect on it. With sodium amalgam the following are formed: benzoaldehyde, benzyl alcohol and other products of complex composition. Chlorine and bromine, as well as iodine, act substitutively in the presence of iodic acid; fuming nitric acid produces nitrobenzoic acids, and fuming sulfuric acid produces sulfobenzoic acids. In general, the hydrogens of the phenyl group in the acid can be replaced one after another by various residues, and a huge number of diverse compounds are formed, of which several isomeric forms are known for many. Of the derivatives of B. acid formed through substitution in the carboxyl group, the simplest will be the following:

Benzoyl chloride, the acid chloride of B. acid, C6H5-COCl, was first obtained by Liebig and Wöhler in 1832 by treating bitter almond oil with dry chlorine; it is also formed by the action of phosphorus pentachloride or trichloride on benzoic acid or phosphorus oxychloride on benzoinonate salt. Colorless liquid with a pungent odor, st. weight 1.324 (at 0°), boiling at 198°; hardens in the cooling mixture into crystals (melting at -1°). Hot water quickly decomposes into hydrochloric and fermented acids; easily enters into double decompositions with a number of substances; Thus, under the action of ammonia, Liebig and Wöhler obtained from it benzamide, or B. acid amide, C6H5-CONH3, a crystalline substance that melts at 128°, sp. weight 1.341 (at 4°), soluble in hot water, alcohol and ether. Benzamide is also obtained by heating B. acid with ammonium thiocyanate. Water-removing substances easily convert it into B. acid nitrile, benzonitrile or phenyl cyanide - C6H5CN. This latter is also obtained from the potassium salt of sulfobenzoic acid and potassium cyanide. The substance is a liquid with a bitter almond odor, boiling at 190°, bpm. weight 1.023 (at 0°), solidifying upon strong cooling into a solid mass. Difficult to dissolve in boiling water and readily soluble in alcohol and ether.

Methods of obtainingmonobasic carboxylic acids of the aromatic series

Monobasic aromatic carboxylic acids can be prepared by all general methods known for fatty acids.

Oxidation of alkyl groups of benzene homologues. This is one of the most commonly used methods for producing aromatic acids:

Oxidation is carried out either by boiling the hydrocarbon with an alkaline solution of potassium permanganate, or by heating it in sealed tubes with dilute nitric acid. Typically this method gives good results. Complications occur only in cases where the benzene ring is destroyed by the action of oxidizing agents.

Oxidation of aromatic ketones. Aromatic ketones are easily prepared by the Friedel-Crafts reaction. Oxidation is usually carried out using hypochlorites according to the following scheme:

However, other oxidizing agents can be used. Aceto derivatives oxidize more easily than hydrocarbons.

Hydrolysis of trihalogen derivatives with halogens at one carbon atom. When toluene is chlorinated, three types of chlorine derivatives are formed: benzyl chloride (used to obtain benzyl alcohol), benzylidene chloride (to obtain benzoaldehyde), benzotrichloride (processed into benzoic acid and benzoyl chloride). Direct hydrolysis of benzotrichloride does not proceed well. Therefore, benzotrichloride is converted by heating with benzoic acid into benzoyl chloride, which then, upon hydrolysis, easily gives benzoic acid:

Hydrolysis of nitriles:

This method is widely used in the fat row. In the aromatic series, the starting nitriles are obtained from diazo compounds, from halogen derivatives by exchange with copper cyanide in pyridine or by fusion of sulfonates with potassium cyanide. Acid nitriles with a nitrile group in the side chain are obtained by an exchange reaction from halogen derivatives.

Reaction of aromatic hydrocarbons with halogen derivatives of carbonic acid

The carboxyl group can be introduced into the nucleus through a reaction similar to the Friedel-Crafts synthesis of ketones. The catalyst is aluminum chloride:

Reactions of organometallic compounds with CO 2 :

Lithium or organomagnesium compounds are usually used.

Acid chlorides are prepared by reacting with thionyl chloride or phosphorus pentachloride acids:

Anhydrides are obtained by distillation of a mixture of acid and acetic anhydride in the presence of phosphoric acid or by the action of acid chlorides on salts:

When benzoyl chloride reacts with sodium peroxide, crystalline benzoyl peroxide is obtained:

When an alcoholate reacts with benzoyl peroxide, a salt of perbenzoic acid (benzoyl hydroperoxide) is obtained. This acid is used to obtain oxides from unsaturated compounds (Prilezhaev reaction):

Benzene, in the absence of a catalyst, does not react with bromine and chlorine, thereby demonstrating the stability of the three double bonds in its molecule to the action of electrophilic agents. At the same time, the presence of the latter is confirmed by the interaction of benzene with chlorine during irradiation, leading to the formation of hexachlorocyclohexane (hexachlorane):

An interesting reaction involving double bonds is observed when benzene in the liquid phase is irradiated with light with a wavelength of 253.7 nm. Under these conditions, the benzene molecule is rearranged, turning into so-called valence isomers.

Nitrobenzoic acids

The nitration of benzoic acid produces 78%-meta-, 20% ortho- and 2% pair- nitrobenzoic acids. The last two isomers without impurities of other isomers are obtained by oxidation ortho- And pair- nitrotoluenes

Nitrobenzoic acids have stronger acidic properties than benzoic acid (TO= 6.6·10 -5): O- isomer - 100 times, m- isomer - 4.7 times and n-iso measures - 5.6 times. A similar pattern is observed in the case of halogen-substituted acids.

Application

Benzoic acid and its salts have high bactericidal and bacteriostatic activity, which increases sharply with decreasing pH. Due to these properties, as well as non-toxicity, benzoic acid is used:

preservative in the food industry (addition of 0.1% acid to sauces, brines, fruit juices, jams, minced meat, etc.)

in medicine for skin diseases as an external antiseptic (antimicrobial) and fungicidal (antifungal) agent, and its sodium salt as an expectorant.

In addition, benzoic acid and its salts are used in food preservation (food additives E210, E211, E212, E213). Esters of benzoic acid (from methyl to amyl), which have a strong odor, are used in the perfume industry. Various benzoic acid derivatives, such as chloro- and nitrobenzoic acids, are widely used for the synthesis of dyes.

Benzoic acid is used in the production

caprolactam

benzoyl chloride

additive to alkyd varnishes that improves gloss, adhesion, hardness and chemical resistance of the coating

Salts and esters of benzoic acid (benzoates) are of great practical importance.

Sodium benzoate is a food preservative, polymer stabilizer, corrosion inhibitor in heat exchangers, expectorant in medicine.

Ammonium benzoate is an antiseptic, preservative in the food industry, corrosion inhibitor, stabilizer in the production of latexes and adhesives.

Transition metal benzoates are catalysts for the liquid-phase oxidation of alkyl aromatic hydrocarbons to benzoic acid.

Esters of benzoic acid from methyl to isoamyl are fragrant substances. Methyl benzoate is a solvent for cellulose ethers.

Isoamyl benzoate is a component of fruit essences.

Benzyl benzoate is an odor fixer in perfumery, a solvent for fragrant substances, an antiseptic, and a moth repellent.

Precautionary measures:

Causes irritation upon contact with skin.

Inhalation of the aerosol causes a convulsive cough, runny nose, and sometimes nausea and vomiting.

Conclusion

Latin name: Acidum benzoicum

Benzoic acid C6H5COOH is the simplest monobasic carboxylic acid of the aromatic series.

Benzoic acid is colorless crystals, poorly soluble in water, well soluble in ethanol and diethyl ether.

It is used mainly in the form of sodium (high solubility in water) - sodium benzonate, potassium and calcium salts.

Melting point - 122.4°C,

Boiling point - 249°C.

Easily sublimes (one of the methods of production is dry distillation of benzoin resin); distilled with steam.

Benzoic acid (BA) is used in medicine for skin diseases as an external antiseptic (antimicrobial) and fungicidal (antifungal) agent, and its sodium salt is used as an expectorant.

B. and its salts have high bactericidal and bacteriostatic activity, which increases sharply with decreasing pH of the environment.

A reaction with some forms of ascorbic acid (vitamin C) is possible.

In the body, benzoic acid combines with glycine to form harmless hippuric acid, which is excreted in the urine.

The permissible dose of benzoic acid and its salt for humans is 5 mg/kg of body weight per day.

Concentration in recipes: 0.2-0.5% (per 50 g of cream - 0.2 g of sodium benzoate).

The activity of benzoic acid decreases in the presence of nonionic surfactants, proteins and glycerol.

Used in conjunction with other preservatives.

Being fat soluble, it can be used as a preservative for fats, lipsticks, etc. The maximum concentration in cosmetic products is 0.5%.

Salts of benzoic acid - benzoates (for example, sodium benzoate) are also used as preservatives.

Other uses: Benzoic acid esters, which have a strong odor, are used in the perfume industry.

Various benzoic acid derivatives, such as chloro- and nitrobenzoic acids, are widely used for the synthesis of dyes.

B. and its esters are contained in essential oils (for example, clove oil), Tolu and Peruvian balsams, and benzoic resin (up to 20% acid and up to 40% its esters).

Additional Information:

In practice, aqueous solutions of sodium benzoate with a concentration of 5 to 25% are most often used.

To prepare the solution, the required amount of preservative is dissolved in approximately half the required volume of drinking water, heated to 50...80C. After the salt has completely dissolved, add the remaining water to the resulting solution and mix thoroughly. It is recommended to filter the solution through a layer of cotton fabric (calico). If a preservative is dissolved in hard water, the solution may be slightly cloudy, but this does not affect its preservative effect.

When developing a specific recipe for adding a preservative to a product, the following must be taken into account:

the acidity of the environment affects the effectiveness of preservatives - the more acidic the product is, the less preservative needs to be added to it;

as a rule, low-calorie products have a high water content and are easily spoiled, so the amount of preservative added to them should be 30-40% more than recommended for regular products;

the addition of alcohol, a large amount of sugar or other substance exhibiting preservative properties reduces the required amount of preservative.

Literature

1 Zemtsova M.N. Guidelines for completing coursework in organic chemistry.

2. Chemical reagents and preparations Goskhimizdat 1953, Pp. 241-242.

3. Karyakin Yu.V., Angelov I.I. Pure chemicals Ed. 4th, lane and additional M.: Chemistry 1974, pp. 121-122.

4. “Concise chemical encyclopedia” Ed. Soviet Encyclopedia, T.4 M. 1965 Page. 817-826.

5. Petrov A.A., Balyan H.V., Troshchenko A.T. Organic chemistry: Textbook for universities. – St. Petersburg: “Ivan Fedorov”, 2002, Page. 421-427.

6. Gitis S.S., Glaz A.I., Ivanov A.V. Workshop on organic chemistry: -M.: Higher school, 1991. - 303.: ill.

7. Shabarov Yu.S. Organic chemistry: Textbook for universities in 2 books. – M.: Chemistry, 1996.Pp. 558-561, 626-629.

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Appearance. Benzoic acid is colorless, silky, shiny flakes or white crystals and plates;

(or crystalline powder) for low grade acid made in China.

Physical properties of benzoic acid.

Molar mass 122.12 g/mol

Physical properties.

Condition (standard condition) solid

Thermal properties

Melting point 122.4 °C

Boiling point 249.2 °C

Decomposition temperature 370 °C

Specific heat of vaporization 527 J/kg

Specific heat of fusion 18 J/kg

Chemical properties

Solubility in water 0.001 g/100 ml

Description of benzoic acid and differences between different brands.

Benzoic acid was first isolated by sublimation in the 16th century from benzoic resin, hence its name, a rare coincidence in science, when it turned out after Justus von Liebig (a German chemist) determined the structural formula of benzoic acid in 1832, the name coincided with the real formula. Until now, the main way to obtain it is the oxidation of methylbenzene (toluene.)

1 recrystallization of the product and commercial packaging, all Chinese and former Russian manufacturers did exactly this.

In this case, the product is prone to rapid and inevitable caking. Bags of benzoic acid turn into stone, which is difficult to break even by machine.

The purity of such an acid does not exceed 97%; on the labels the Chinese proudly write 99.5%, but this is due to the presence of crystalline hydrates. The actual dry matter content is significantly less.

The second feature of direct crystallization is the presence of a large amount of aldehydes, which causes a sharp, nauseous chemical odor that stings the eyes.

Currently, there are several careless companies engaged in shuffling Chinese benzoic acid under the European DSM BRAND. These fakes can always be distinguished by the presence of benzoic acid in crystals in the bags and their pungent odor.

This benzoic acid has nothing to do with the manufacturer of DSM.

2 production method involves an additional stage, melting benzoic acid crystals and subsequent recrystallization from the melt.

This stage allows you to achieve several goals:

1 The product is obtained in small scales that do not generate dust or cake.

2, due to the high temperature, foreign impurities evaporate and the content of the main substance is 99.9% or 103% of the crystalline hydrate.

A distinctive feature of this acid is that it has flakes rather than crystals and a much milder odor. Only such an acid can be used for synthesis and inhibition. and for food and feed purposes as an additive E210.

Specification for benzoic acid produced by DSM (KALAMA).

A distinctive feature of this DSM (KALAMA) brand: crystallization from the melt, which allows you to obtain a product with a minimum caking coefficient and a significantly lower odor compared to other manufacturers.

Technical characteristics for this brand of benzoic acid:
Flake size 0.5-4.5 mm
Bulk density 540kg/m3

Safety for humans.

Recently, many articles have appeared that provide various data on the terrible dangers of this product. This is greatly untrue.

Benzoic acid can be called a natural compound, since it is present in some berries (blueberries, lingonberries, cranberries), and is also formed in fermented milk products such as yoghurt or yogurt. It allows the berries to resist fungal diseases and mold. So this is one of the few preservatives invented by nature, but of course the correct dosages have not been canceled. If they are exceeded, unpleasant behavior of any chemical ingredient may occur.

Benzoic acid for animals.

Cat lovers should remember that benzoic acid and its salts are extremely dangerous for your pets on their own, even in minute quantities. Therefore, before offering your cat any product from your table, make sure that it does not contain such a preservative. In general, this is one of the many reasons why you should not feed your pets “human” canned food. But for pigs it has long been used in large quantities, but for some reason no one says the word benzoic acid, and all veterinarians know it as the additive VIOVITAL (VevoVitall) (not to be confused with biovetal, different things, although they are consonant), which is what it is in its composition pure 99.9% benzoic acid.

All over the world, benzoic acid is actively used in fattening and raising pigs.

1 Effect of using high-purity benzoic acid 99.9%

When feeding piglets.

10% improvement in piglet weight gain

5% reduction in feed intake.

Reduce odor on and off the farm.

The addition of high-purity benzoic acid (at least 99.9%) leads to acidification of urine.

– After absorption from the intestine, benzoic acid is converted into hippuric acid in the animal’s liver, this acid is easily excreted in the urine. And leads to its intense acidification. At the same time, hippuric acid contains an amine. This leads to a significant reduction in NH4+ NH3 ammonia emissions.

This results in a significant reduction in odor on the pig farm.

In addition, problems with UTI (sows) are reduced

Benzoic acid is also present in the intestinal tract, inhibiting the development of anaerobic bacteria and reducing gas production. Which significantly reduces odor on the surface and external emissions.

Antimicrobial protection of young pigs using high-purity benzoic acid (not less than 99.9%) data from in vitro studies

1./2 inhibitory concentration of benzoic acid was used.

to inhibit 50% of microbial growth.

ACETYLSALICYLIC (2-(ACETYLOXY)-BENZOIC) ACID white crystalline substance, slightly soluble in water, highly soluble in alcohol and alkali solutions. This substance is obtained by reacting salicylic acid with acetic anhydride:

Acetylsalicylic acid has been widely used for more than 100 years as an antipyretic, analgesic and anti-inflammatory drug. There are more than 50 brand names of drugs whose main active ingredient is this substance. This unusual medicine can be called a record holder among medicines. Acetylsalicylic acid is a long-liver in the world of medicines; it officially celebrated its centenary in 1999, and is still the most popular medicine in the world. The annual consumption of drugs containing acetylsalicylic acid exceeds 40 billion tablets.

Another feature of acetylsalicylic acid is that it is the first synthetic medicinal substance. From time immemorial, man has used medicinal plants, then learned to isolate medicinal substances in their pure form from plant extracts, but the first medicine, a complete analogue of which does not exist in nature, was acetylsalicylic acid.

There is a similar substance in nature: salicylic acid. This compound is found in willow bark and its healing properties have been known since ancient times. A decoction of willow bark was recommended by Hippocrates as an antipyretic, analgesic and anti-inflammatory agent. In 1828, the German chemist Büchner isolated a substance from willow bark that he named salicin (from the Latin name for willow Salix). A little later, pure salicylic acid was obtained from salicin, and it was proven that it has medicinal properties. Salicin, isolated from willow bark, a waste product from basket making, was used as a medicine, but it was produced in very small quantities and was expensive. In 1860, the German chemist A. Kolbe developed a method for the synthesis of salicylic acid by reacting sodium phenolate with carbon dioxide, and soon a plant for the production of this substance appeared in Germany:

Both salicin and cheaper synthetic salicylic acid were used in medical practice, but salicylic acid was not widely used as a medicine for internal use. Due to its high acidity, it causes severe irritation to the mucous membranes of the mouth, throat, and stomach, and its salts salicylates have such a taste that most patients felt sick from them.

A new drug that has the same therapeutic properties, but less pronounced side effects, as salicylic acid, was discovered and patented by the German company Bayer. According to the official version, the father of the chemist Felix Hoffman, who worked at the company, suffered from rheumatism, and the loving son set out to obtain a substance that would alleviate the suffering of his rheumatic father, but would have a more pleasant taste than salicylates and would not cause stomach pain. In 1893, he discovered the desired properties in acetylsalicylic acid, first obtained from salicylic acid forty years earlier, but which did not find application. Hoffman developed a method for producing pure acetylsalicylic acid, and after testing the drug on animals (by the way, they were also carried out for the first time in history), in 1899 Bayer patented the trademark aspirin - the name by which this medicine is best known. It is believed that the name of the medicine was given in honor of St. Aspirinus, the patron saint of all headache sufferers, although there is a more prosaic explanation. Salicylic acid was often called spirsaeure at the time because it was also found in the meadowsweet plant (spiraea). And the brand name is simply an abbreviation of the name accepted at that time for acetylsalicylic acid, acetylspirsaeure. By the way, salicylic acid has also found its place in medicine; its solution salicylic alcohol treats skin inflammatory processes and is included in many cosmetic lotions.

Acetylsalicylic acid lowers temperature, reduces local inflammatory processes, and relieves pain. It also thins the blood and is therefore used when there is a risk of blood clots. It has been proven that long-term use of a small dose of acetylsalicylic acid by people prone to cardiovascular diseases significantly reduces the risk of stroke and myocardial infarction. At the same time, the drug is absolutely devoid of the terrible drawback of many painkillers - addiction does not develop to it. It would seem like an ideal medicine. Some people are so accustomed to this drug that they take it with or without reason, at the slightest pain or just “just in case.”

But in no case should we forget that medications should not be abused. Like any medicine, acetylsalicylic acid is unsafe. An overdose can lead to poisoning, manifested by nausea, vomiting, stomach pain, dizziness, and in severe cases, toxic inflammation of the liver and kidneys, damage to the central nervous system (disorder of motor coordination, confusion, convulsions) and hemorrhages.

If a person is taking several medications at the same time, you need to be especially careful. Some medications are incompatible with each other, and this can cause poisoning. Acetylsalicylic acid increases the toxic effects of sulfonamides, enhances the effect of painkillers and anti-inflammatory drugs such as amidopyrine, butadione, analgin.

This medicine also has side effects. Just like salicylic acid, although to a much lesser extent, it leads to irritation of the mucous membranes of the stomach. To avoid negative effects on the gastrointestinal tract, it is recommended to take this medicine after meals with plenty of liquid. The irritating effect of acetylsalicylic acid is enhanced by wine alcohol.

Much of the irritating effect of aspirin is due to its poor solubility. If you swallow a tablet, it is slowly absorbed; an undissolved particle of the substance may “stick” to the mucous membrane for some time, causing irritation. To reduce this effect, simply crush an aspirin tablet into powder and drink it with water; sometimes alkaline mineral water is recommended for this purpose, or buy soluble forms of aspirin effervescent tablets. However, it should be borne in mind that these measures do not reduce the risk of developing gastrointestinal bleeding due to the effect of the drug on the synthesis of “protective” prostaglandins in the gastric mucosa. Therefore, it is better not to abuse acetylsalicylic acid, especially for people with gastritis or stomach ulcers.

Sometimes the effect of reducing blood clotting may be undesirable or even dangerous. In particular, medications containing acetylsalicylic acid are not recommended for use in the week before surgery, as it increases the risk of unwanted bleeding. Pregnant women and young children should not take acetylsalicylic acid unless absolutely necessary.

Despite the fact that acetylsalicylic acid has been known for so long and is very widely used as a medicine, an explanation of the mechanism of its action on the body appeared only in the 1970s. British scientist J. Vane received the Nobel Prize in Physiology or Medicine and the title of knight from Queen Elizabeth II in 1982 for his work studying the physiological effects of acetylsalicylic acid. Wayne discovered that acetylsalicylic acid blocks the synthesis of certain hormone-like substances in the body - prostaglandins, which are responsible for the regulation of many body functions, in particular, it inhibits the synthesis of prostaglandins that cause inflammation. Side effects of acetylsalicylic acid are explained by a slowdown in the synthesis of other prostaglandins responsible for blood clotting and regulation of the formation of hydrochloric acid in the stomach.

Further research showed that not all of the properties of this substance are associated with blocking the synthesis of prostaglandins. The mechanism of action of acetylsalicylic acid is complex and not fully understood, and its properties are still the object of study by many scientific teams. In 2003 alone, about 4,000 scientific articles were published on the intricacies of the physiological effects of this substance. Scientists, on the one hand, are finding new uses for an old drug for example, recent studies have revealed the mechanism of the effect of acetylsalicylic acid on lowering blood sugar levels, which is important for patients with diabetes. On the other hand, based on research, new drugs for acetylsalicylic acid are being developed, the side effects of which are minimized. Obviously, acetylsalicylic acid will provide work for more than one generation of scientists, physiologists and pharmacists.

Materials on the Internet: http://www.remedium.ru

http://www.brandpro.ru/world/histories/h02.htm

http://www.inventors.ru/index.asp?mode=4212

http://www.roche.ru/press_analitic_medpreparat_apr.shtml

Ekaterina Mendeleeva

The substance has the symbol E210 and owes its name to benzoin gum, from which it was first isolated about five centuries ago.

It has an antimicrobial effect, and in the last century it began to be widely used in medicine and for preserving a variety of products. This substance will be discussed in, as well as its use today.

Properties of benzoic acid

The basic properties and its structure were studied in the 19th century. In appearance, the preservative is a crystalline powder, which can be unmistakably distinguished from others by its characteristic odor.

In water benzoic acid dissolves poorly (only 0.3 grams of crystalline powder per glass).

Therefore, if necessary, they usually use. But benzoin is soluble in water-free ethyl alcohol, in addition in substances such as fats, and it is easy to obtain its solution in 100 g of oil and 2 g of E210.

At a temperature of 122.4 °C the powder melts, and at 249 °C the substance boils. Benzoic acid formula has the form: C 6 H 5 COOH.

The substance is classified as a monobasic aromatic substance. E210 actively reacts with proteins.

To carry out a chemical reaction on the quality of E210 and benzoic acid salts, pour a little benzoin into a test tube and drop a small amount of 10% NaOH solution.

It is quite easy to distinguish benzoin from sodium benzoate by chemical characteristics. The easiest way to do this is with litmus.

If so, then it's benzoate sodium, benzoic acid gives a reaction, so the piece of paper .

The substance is harmless to humans and is easily excreted from the body, into which it enters with food, cosmetics and medicines.

However, when consumed with products containing apricot, life-threatening benzene is formed, which has a harmful effect on the functioning of the liver and kidneys. Therefore, the use of preservatives in food products is strictly dosed.

Cats react to E210 in many ways different from their owners. For them, the daily intake should be no more than hundredths of a milligram.

This suggests that it is better not to feed your pets canned food or foods containing benzoin.

Once in the human body, E210 promotes the production of the extremely necessary vitamin B10.

This is a very valuable property, because if there is a lack of this substance, very serious problems can arise and unpleasant diseases can develop.

A person with a lack of benzoin may experience irritability and weakness, as well as depression and headaches.

Uses of benzoic acid

The substance is valuable because it reduces the activity of enzymes in the structure of microbes, killing them, which explains its disinfectant properties.

This quality has found active use of benzoic acid and is successfully used for the manufacture of medicinal compositions for coughs, expectorants and antiseptics, as well as special preparations called fungicides, used in agriculture to protect a variety of cultivated plants.

Effectively and widely used for the treatment of skin diseases. By killing fungi, the substance perfectly helps eliminate various fungal infections.

It perfectly fights sweaty feet. For effective action, a series of baths are made with the addition of E210 crystals, and these give the most positive results.

Preparations made from E210 can help with diseases (low coagulability or thickening).

They perfectly help nursing mothers, significantly activating lactation and improving the quality of breast milk.

Medicines containing benzoin are indicated for children who experience slow growth, helping to eliminate such developmental deficiencies. Preparations from E210 are also prescribed by doctors for patients with anemia.

Benzoic acid, salicylic, Vaseline - are a group of products that, when combined, have many beneficial properties.

Creams, ointments and lotions are produced from them, which perfectly cure painful skin growths and calluses.

Successfully used benzoic acid in cosmetics. It is part of effective hair treatment products and serves as a necessary basis for the composition of useful medications that protect the scalp from fragility and loss.

Almost all products for rejuvenating and eliminating skin problems contain benzoin.

E210 is added to ointments that perfectly relieve scabies. It is used to produce deodorants and perfumes.

The substance is also used in the chemical industry as an effective and strong reagent in the synthesis of numerous types of organic substances.

The properties of the preservative are invaluable in cooking and are successfully used in bakeries and confectioneries.

Without it, it is unthinkable to prepare many types of vegetable and vegetable pickles, fruit and berry jams, marinate some types of meat and fish, as well as produce margarine and substitutes useful for diabetics.

Without this, there would be no sweet candies, delicious liqueurs, special seasonings, many varieties of ice cream and aromatic chewing foods.

Benzoic acid esters are successfully used to stabilize plastics, which is an important part of the process in the manufacture of technical and children's products.

Preparation of benzoic acid

They were first isolated from benzoin resin. In nature, as a result of the activity of microbes, the substance is obtained during the decomposition of hippuric acid and is formed naturally in curdled milk and yoghurts, and other fermented milk products.

It is also found in clove oil, and is found naturally in lingonberries, blueberries and cranberries.

In the old days for obtaining benzoic acid used the hydrolysis method using various catalysts.

But today this method has lost its relevance. The most profitable and widespread modern production method is synthesis through the oxidation of toluene.

The process is remarkable in that it does not contaminate the environment with harmful substances, and the raw materials used are quite cheap. Impurities such as benzyl alcohol, benzyl benzoate and others are released from the substance.

Benzoic acid price

Buy benzoic acid you can freely. No documents are required for this. And it is sold to both legal entities and any individuals.

To complete such a transaction, you should find a suitable company in your city, country or abroad that sells reagents.

Such enterprises and companies can operate in cash, and in some cases, by bank transfer.

The substance can also be purchased in chemical laboratories for almost nothing.

It is advisable to look for great deals with photos, addresses, descriptions and reviews in.

You can also find out about offers for the wholesale sale of aromatic benzoins online.

E210 crystalline powder can be purchased in kilograms and packaged in bags, the weight of which is usually 25 kg.

The price depends on the quality of the product, which ranges from 74 to 150 rubles per kg.

Imported products usually have higher prices, reaching up to 250 rubles/kg. Benzoic Acid Powder from Romania and Holland sell at a price of 105 rubles/kg.

Benzoin, packaged in bags, is sold at a price ranging from 650 to 1350 rubles. per bag.

A substance of this quality is intended for medical purposes and can be used as an antiseptic, antifungal and antibacterial agent.

Preparation of C6H5COOH:

Main methods:

1. By oxidation of a wide variety of benzene derivatives having one side chain, for example, toluene, ethylbenzene, benzyl alcohol, etc.: C6H5CH3 ® C6H5COOH

2. From benzonitrile, which is hydrolyzed with an acid or alkali for this purpose: 2H2 O C6H5CN ¾¾® C6H5COOH + NH3

HOOC-CH2 + H2O = HOOC-CH2(NH2) + C6H5-COOH.

C6H5Br + 2Na + CO2 = C6H5CO2Na + NaBr.

Benzoyl chloride, the acid chloride of B. acid, C6H5-COCl, was first obtained by Liebig and Wöhler in 1832 by treating bitter almond oil with dry chlorine; it is also formed by the action of phosphorus pentachloride or trichloride on benzoic acid or phosphorus oxychloride on benzoinonate salt. Colorless liquid with a pungent odor, st. weight 1.324 (at 0°), boiling at 198°; hardens in the cooling mixture into crystals (melting at -1°). Hot water quickly decomposes into hydrochloric and fermented acids; easily enters into double decompositions with a number of substances; Thus, under the action of ammonia, Liebig and Wöhler obtained from it benzamide, or amide of B. acid, C6H5-CONH2, a crystalline substance that melts at 128°, sp. weight 1.341 (at 4°), soluble in hot water, alcohol and ether. Benzamide is also obtained by heating B. acid with ammonium thiocyanate. Water-removing substances easily convert it into B. acid nitrile, benzonitrile or phenyl cyanide - C6H5CN. This latter is also obtained from the potassium salt of sulfobenzoic acid and potassium cyanide. The substance is a liquid with a bitter almond odor, boiling at 190°, bpm. weight 1.023 (at 0°), solidifying upon strong cooling into a solid mass. Difficult to dissolve in boiling water and readily soluble in alcohol and ether.

Methods of obtaining monobasic carboxylic acids of the aromatic series

Monobasic aromatic carboxylic acids can be prepared by all general methods known for fatty acids.

Oxidation of alkyl groups of benzene homologues. This is one of the most commonly used methods for producing aromatic acids:

Oxidation of aromatic ketones. Aromatic ketones are easily prepared by the Friedel-Crafts reaction. Oxidation is usually carried out using hypochlorites according to the following scheme:

However, other oxidizing agents can be used. Aceto derivatives oxidize more easily than hydrocarbons.

Hydrolysis of nitriles:

Benzoic acid ba oh 2. Benzoic acid - abstract

Selecting an amidation catalyst and studying the conversion of m-toluyl in its presence acids in N,N-diethyl-m-toluamide

Synthesis of malonic diethyl ether acids. Properties and basic methods for obtaining esters

When feeding piglets.

Reduce odor on and off the farm.